1. Field of the Invention
The present invention relates to a steering wheel of a vehicle, and more particularly, to a steering wheel having an air bag.
2. Background
A typical steering wheel includes an annular gripping ring and a pad. The pad is located at the center of the ring and is connected to the ring by spokes. A metal ring core is embedded in the gripping ring while a metal spoke core is embedded in the spokes. The ring core and the spoke core are covered by a surface layer formed from, for example, polyurethane foam. A boss plate is connected to the spoke core below the pad to connect the steering wheel to a steering shaft. The boss plate is fastened to the distal end of a steering shaft by a nut.
An air bag device is mounted on the steering wheel after the spoke core and the boss plate are secured to the steering shaft by the nut. The pad is then mounted over the air bag device.
Japanese Unexamined Patent Publication No. 3-169764 discloses such a steering wheel assembling method. The air bag device includes an inflator, an air bag, a ring retainer and a bag holder. The pad includes a bracket projecting downwardly. The inflator, the air bag, the ring retainer and the bag holder are secured to one another by bolts. The bag holder is then fastened to the bracket of the pad by bolts. The bag holder is further fastened to the spoke core by bolts.
In the method of this Japanese publication, the bolts are used for fastening the parts to one another. This complicates the mounting of the steering wheel and increases the number of parts.